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ARS Home » Southeast Area » Mississippi State, Mississippi » Crop Science Research Laboratory » Corn Host Plant Resistance Research » Research » Publications at this Location » Publication #314068

Research Project: Genetic Improvement of Maize with Enhanced Resistance to Aflatoxin and Insects

Location: Corn Host Plant Resistance Research

Title: DNA fingerprinting of maize seed lots to establish genetic purity using SSR markers.

Author
item SETIMELA, P. - International Maize & Wheat Improvement Center (CIMMYT)
item Warburton, Marilyn
item ERASMUS, T. - Incotec

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/2/2015
Publication Date: 3/1/2016
Citation: Setimela, P.S., Warburton, M.L., Erasmus, T. 2016. DNA fingerprinting of maize seed lots to establish genetic purity using SSR markers.South African Journal of Plant Science. 33(2):141-148.

Interpretive Summary: In some countries in sub-Saharan Africa (SSA), seed of hybrid maize is not available to farmers. Therefore, many of these farmers grow open pollinated maize varieties (OPVs), because seed of maize OPVs can be saved and replanted for several seasons with minimal yield reduction due to inbreeding as compared to traditional farmer (landrace) varieties. However, OPVs are genetically highly mixed, and some local seed suppliers attempt to take advantage of this to adulterate seed bags with cheaper food grain. Even inadvertent pollen or seed contamination is difficult to avoid during seed increases. If smallholder farmers purchase and sow these kernels, poor plant stands and low grain yields result. A bulked DNA fingerprinting method which can detect such mixing or mislabeling of OPVs has been developed. This study seeks to use this method to determine the level of genetic purity among 35 seed lots of ZM521, a popular African OPV, maintained by various sources. In addition to the ZM521 seed lots, 13 other OPVs and two hybrids were studies as controls. Using this method, the 53 seed lots grouped according to the source of foundation seed from which each seed lot was derived, and genetic divergence was large between the groups. In some cases, it could be determined that the ZM521 were no longer pure, and had been mixed or mislabeled at some point.

Technical Abstract: Most countries in sub-Saharan Africa (SSA) grow open pollinated maize varieties (OPVs) because seed of maize OPVs can be recycled for several seasons with minimal yield reduction due to inbreeding as compared to hybrids. However, OPVs are heterogeneous, and some local seed suppliers attempt to take advantage of this to adulterate seed bags with cheaper food grain. Even inadvertent pollen or seed contamination is difficult to avoid during seed increases. If smallholder farmers purchase and sow these kernels, poor plant stands and low grain yields result. A bulked DNA fingerprinting method which can detect such mixing or mislabeling of OPVs has been developed. This study seeks to use this method to determine the level of genetic purity among 35 seed lots of ZM521, a popular African OPV, maintained by various sources. In addition to the ZM521 seed lots, 13 other CIMMYT OPVs, and the hybrids SC513 and SC403 From each seed lot, 20 seeds were randomly selected and sown for DNA extraction, and equal amounts of DNA were mixed from each seedling. The bulked DNA was used for simple sequence repeat (SSR) analysis on an automatic DNA sequencer, allowing allele frequency to be determined from the bulk using peak intensity. Fifteen SSR markers were used to determine the genetic purity of the various seed lots of ZM521. The 53 seed lots grouped according to the source of foundation seed from which each seed lot was derived, and genetic divergence was large between the groups.